Planetary health research digest
Authors: Sam Hinsley
Journal: The Lancet Planetary Health (2020)

Reducing fossil fuel combustion is essential to any efforts to meet the 1·5°C and 2·0°C targets of the Paris Agreement. The capacity to reduce greenhouse gas emissions within global food production is less appreciated though. Michael Clark (University of Oxford, UK) and co-authors modelled future emissions from the global food system, as well as potential scenarios for reducing them to see if they were compatible with the 1·5°C and 2·0°C goals. They report that, even with the complete elimination of fossil fuel emissions, business as usual in food systems, the 1·5°C goal would be missed within 30–45 years, and meeting the 2·0°C goal would be unlikely. However, if ambitious emission reduction strategies—including a shift to plant-based diets, efficiency improvements, and halving waste—could be implemented by 2050, meeting the 2·0°C target could be attainable, and partial implementation of simultaneous strategies could have similar benefits. While food system emissions may seem inevitable, the authors show this is not the case, and that addressing them will be critical to meeting the Paris goals. Invasions by non-native species pose major threats to biodiversity in environments around the world. Despite the known problems they pose, the complex interactions among the many drivers involved in their spread have limited quantitive investigation of the issue. Franz Essl and Bernd Lenzner (University of Vienna, Austria) and co-authors instead used an expert-based assessment approach to study how selected drivers affected biological invasions in various socioecological settings and under different scenarios; 36 experts completed the authors’ survey. Under the best case scenarios for future changes in each driver, trade and transport, socioeconomic development, and climate change were rated as the most relevant drivers of invasions in all socioecological contexts. Other drivers were more context dependent, such as human demography and migration, which was most important in tropical and subtropical regions and for invertebrates, vertebrates, and vascular plants. Under worst-case scenarios, nearly all drivers played a significant role in enabling major impacts on biodiversity by alien species. By identifying the key drivers of alien species invasions around the world, the authors provide evidence that policy interventions can be developed from. Ending poverty in all forms everywhere is the first of the Sustainable Development Goals, and while major progress has been made in the past 30 years, the world was still off track to achieving this goal by 2030, even before the COVID-19 pandemic. Finding new funds to alleviate poverty while ensuring sustainable development has never been more necessary. One possible option could be the use of revenue from carbon taxes. Shinichiro Fujimori (University of Kyoto, Japan) and co-authors created a model to investigate the scale of revenues if carbon taxes were established consistently worldwide and how this compares to national and global poverty gaps (ie, the income deficit relative to the poverty line). Under the middle-of-the road socioeconomic scenario and with mitigation efforts consistent with a 2·0°C temperature increase, the total revenue was estimated at US$1600 billion in 2030, while the global poverty gap was $84 billion. Notably, many lower income countries would not be able to cover their own poverty gaps, while most revenue comes from high-income OECD and European economies, as well as large middle-income countries like India and China. The authors show the opportunity for poverty reduction that carbon taxes could bring, but highlight the need for international co-operation if any systematic progress is to be made. Traditionally, the media has played a large role in setting the public discourse agenda in democratic societies. With the rise of social media, however, politicians can communicate with the public directly. The clearest example of an individual politician shaping public discourse and media reporting through their own social media channels is the US President, Donald Trump. Looking at how politicians’ social media posts and mainstream media coverage interact, Stephan Lewandowsky (University of Bristol, UK), Michael Jetter, and Ullrich Ecker investigated how President Trump responded to harmful media coverage in his tweets, and how these tweets affected subsequent reporting. They used coverage of the Mueller investigation as an example of potentially harmful news reporting and tweets on subjects like jobs, China, and immigration as possible diversionary subjects. News coverage of the Mueller investigation was associated with increases in the number of President Trump's tweets on his preferred subjects, which in turn were associated with reductions in coverage of the investigation in subsequent days. The findings indicate that social media is a powerful tool for politicians to redirect the public discourse away from subjects harmful to themselves and that mainstream media should be looking out for this type of manipulation, whether intentional or not.